I have used this installation for my fish finders on the last 3 Kayaks I have owned and will continue to use it. Many have asked does the Ducer move? No, I have dropped my kayak off the roof of my Ford Explorer firs thing I checked was the Ducer, and it was still perfectly in place. Readings are great and just as accurate as if it were in water +/- a degree or two with temp.
http://www.youtube.com/watch?v=3u1d3_UeD3k
http://www.youtube.com/watch?v=GEZ9_...eature=related
I know many are going with the permanent wet mount setup, but I encourage you to think out of the box and try something new.